Any tricks for finding a leak in fuel line ?

I'm with @Ceedawg /post 32.
If you put gearclamps on that line, then you need two per side with the screws staggered 180*, else the pump will suck air there. And because it is higher than the fuel level in the tank, it does not leak liquid. And at atmospheric pressure (engine off) it doesn't leak anything at all.
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One thing nobody mentioned is that when HOT fuel under pressure passes over a sharp point, it tends to form bubbles there. IDK what the bubbles are, I just see them forming. Same happens when the hot fuel passes from a high-pressure area to a low pressure area, like into the float bowl.
To help stop that, I put the filter at the back of the car, and run a one-piece hardline from the low-pressure pump to the carb, with no anchor points to the hot engine, which runs at 207*F . After that I just run the engine at WOT most of the time, so there is never any fuel-pressure to speak of...... lol.
Oh, I almost forgot, my fuel line is right in the path of the air coming thru the rad, pulled in by the 7-blade, high attack-angle, all-steel fan, so it sits in a constant bath of about 180* air. Once the hood is closed, that is about the coolest temp you will find under there.
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BTW-1
I have been running 87E10, which is "up to 10%" alcohol, in my combo since 1999 with ZERO problems. I mean nil/nada/nucht/nietski, and zilch.
All this yakitty-yak about alcoholized fuels being a problem is, IMO, just that.

BTW-2
Gasoline is made up of many, many components.
The lightest compounds in the fuel are said to boil at 95*F, at STP (Standard Temperature and Pressure). At 4.5 psi inside the hot fuel line, this condition does not exist. But once the fuel is in the bowl, sitting on an engine that is over 200*F, literally a hot-plate, you can bet that those lighter components are very eager to go anywhere but down into the engine.
When you shut your hot engine off; within seconds those compounds are evaporating. As the float-bowl empties, the fuel-valve opens and the pressure between the pump and bowl drops to zero and the fuel in that line begins to boil. Pretty soon all the VOCs (Volatile Organic Compounds) are boiled off, and all you have left are the heavier components, some of which require over 400* to break down.
Next morning you come out, and crank and crank and crank, because your engine cannot create the heat to ignite those heavy compounds. Finally your pump primes and pushes some fresh fuel with the lighter VOCs, up into the bowls, and Shazzam! she lites up.
Granted; premium fuel does not have those same light VOCs in it, so this is less of a problem. But Premium has other stuff in it, that slows its burn rate, to help prevent detonation. I call it slowgaz, and I don't want no stinking slowgaz in my engine . So I made 87E10 work. Cuz you know; gasohol has oxygen in it, lots of oxygen. Ok not lots, up to 35% by weight IIRC, but neither does the atmosphere, being less than 20% oxygen by weight....... at sealevel. So it's relative. The other 80% is mostly nitrogen, which really serves no useful function as a fuel. Yet there it is, free/no extra charge, thanks be to the Ancient of Days.
Think of it this way; By running 10% ethanol, I just eliminated the compressing of a portion of the useless nitrogen; Hooray free horsepower. But more importantly I injected liquid oxygen at the rate of 35% per pound of that gasohol.
And people call me crazy for burning it!
And they say I can't go as fast as I do go in the Eighth.
And they say it's impossible to get 32mpg out of any 360.
To which I have a standard reply; Just cuz your engine cannot do it, does not mean it cannot be done.
But I digress, lol.